Commit c01c55a3 authored by Paul Durrant's avatar Paul Durrant Committed by Sean Christopherson
Browse files

KVM: x86/xen: separate initialization of shared_info cache and content 



A subsequent patch will allow shared_info to be initialized using either a
GPA or a user-space (i.e. VMM) HVA. To make that patch cleaner, separate
the initialization of the shared_info content from the activation of the
pfncache.

Signed-off-by: default avatarPaul Durrant <pdurrant@amazon.com>
Reviewed-by: default avatarDavid Woodhouse <dwmw@amazon.co.uk>
Link: https://lore.kernel.org/r/20240215152916.1158-11-paul@xen.org


Signed-off-by: default avatarSean Christopherson <seanjc@google.com>
parent 721f5b0d

arch/x86/kvm/xen.c

+32 −23
Original line number Diff line number Diff line
@@ -34,42 +34,33 @@ static bool kvm_xen_hcall_evtchn_send(struct kvm_vcpu *vcpu, u64 param, u64 *r); 


DEFINE_STATIC_KEY_DEFERRED_FALSE(kvm_xen_enabled, HZ);



static int kvm_xen_shared_info_init(struct kvm *kvm, gfn_t gfn)

static int kvm_xen_shared_info_init(struct kvm *kvm)

{

	struct gfn_to_pfn_cache *gpc = &kvm->arch.xen.shinfo_cache;

	struct pvclock_wall_clock *wc;

	gpa_t gpa = gfn_to_gpa(gfn);

	u32 *wc_sec_hi;

	u32 wc_version;

	u64 wall_nsec;

	int ret = 0;

	int idx = srcu_read_lock(&kvm->srcu);



	if (gfn == KVM_XEN_INVALID_GFN) {

		kvm_gpc_deactivate(gpc);

		goto out;

	}

	read_lock_irq(&gpc->lock);

	while (!kvm_gpc_check(gpc, PAGE_SIZE)) {

		read_unlock_irq(&gpc->lock);



	do {

		ret = kvm_gpc_activate(gpc, gpa, PAGE_SIZE);

		ret = kvm_gpc_refresh(gpc, PAGE_SIZE);

		if (ret)

			goto out;



		read_lock_irq(&gpc->lock);

	}



	/*

	 * This code mirrors kvm_write_wall_clock() except that it writes

	 * directly through the pfn cache and doesn't mark the page dirty.

	 */

	wall_nsec = kvm_get_wall_clock_epoch(kvm);



		/* It could be invalid again already, so we need to check */

		read_lock_irq(&gpc->lock);



		if (gpc->valid)

			break;



		read_unlock_irq(&gpc->lock);

	} while (1);



	/* Paranoia checks on the 32-bit struct layout */

	BUILD_BUG_ON(offsetof(struct compat_shared_info, wc) != 0x900);

	BUILD_BUG_ON(offsetof(struct compat_shared_info, arch.wc_sec_hi) != 0x924);
@@ -639,12 +630,30 @@ int kvm_xen_hvm_set_attr(struct kvm *kvm, struct kvm_xen_hvm_attr *data) 
		}

		break;



	case KVM_XEN_ATTR_TYPE_SHARED_INFO:

	case KVM_XEN_ATTR_TYPE_SHARED_INFO: {

		int idx;



		mutex_lock(&kvm->arch.xen.xen_lock);

		r = kvm_xen_shared_info_init(kvm, data->u.shared_info.gfn);



		idx = srcu_read_lock(&kvm->srcu);



		if (data->u.shared_info.gfn == KVM_XEN_INVALID_GFN) {

			kvm_gpc_deactivate(&kvm->arch.xen.shinfo_cache);

			r = 0;

		} else {

			r = kvm_gpc_activate(&kvm->arch.xen.shinfo_cache,

					     gfn_to_gpa(data->u.shared_info.gfn),

					     PAGE_SIZE);

		}



		srcu_read_unlock(&kvm->srcu, idx);



		if (!r && kvm->arch.xen.shinfo_cache.active)

			r = kvm_xen_shared_info_init(kvm);



		mutex_unlock(&kvm->arch.xen.xen_lock);

		break;



	}

	case KVM_XEN_ATTR_TYPE_UPCALL_VECTOR:

		if (data->u.vector && data->u.vector < 0x10)

			r = -EINVAL;